Conversion of hydrocarbons with the use of hydrogen donor diluents



A. w. LANGER, JR. ETAL 3,252,883 CONVERSION OF HYDROCARBONS WITH THE USEOF HYDROGEN DONOR DILUENTS 2 Sheets-Sheet l lnvenrors Purenr AhornevArrhur W. L unger,dr. John A. Hmhcky w 15] MN: 2% mm 07 355 J 5 2w oz;zwwo% I mm 239; mm m vol 68 I w mm ozaauo ow vN mm Tail w mm vm {m 9 6w8 N E 5 mm F mnmum mm in 2 ww ozimolom z 8 i 9 May 24, 1966 Filed NOV.6, 1962 May 24, 1966 A. w. LANGER, JR. ETAL 3,252,888

CONVERSION OF HYDROCARBONS WITH THE USE OF HYDROGEN DONOR DILUENTS FiledNov. 6, 1962 2. Sheets-Sheet 2 mw ll N8 f\ w m NN2 m 1 m 2% $1 3m 93 $9mm? a 3&1 2 a 5mm mum 2m 02525894 3N $251539: NmN wm- NON w m: NNAWP wONm2 QNA mom 9 NR 4 M 59 mm EV- mm: 9.; m9 2 mm 4 oz 2mo. omn v: 3: 87*NF:

Arthur W. Longer, Jr. John A. Hinlicky \nVenTOfS By W V PctenrAfiorneyUnited States Patent 0 3,252,888 CONVERSION OF HYDRGCARBONS WITH THE USEOF HYDROGEN DGNGR DTLUENTS Arthur W. Langer, In, Watchung, and John A.Hiniicky,

Irvington, N..l., assignors to Esso Research and Engineering Company, acorporation of Delaware Filed Nov. 6, 1962, Ser. No. 235,660 12 Claims.(Cl. 208-56) This invention relates to the conversion of high boilinghydrocarbons to lower boiling hydrocarbons. More particularly, theinvention relates to the conversion of high boiling hydrocarbons tonaphtha and/ or motor fuel gasoline in an integrated process involvinghydrocracking of a gas oil fraction and utilizing hydrogen donor diluentcracking in such a manner as to produce ample quantities of aromatichydrocarbons which can be hydrogenated partially to produce excellenthydrogen donor diluents for non-catalytic hydrogen donor diluent cracking (HDDC) of residual oils or bottoms fractions.

The aromatic hydrocarbon bottoms from hydrocraclo ing gas oil are usedon a once-through basis or with recycle as diluents for the HDDCconversion of residual oils.

Integration of the HDDC-hydrocracking processes with gas oil catalyticcracking and naphtha reforming produces a balanced refinery operationwith complete residuum conversion which is self-sufficient with respectto hydrogen and hydrogen donor diluent. On crude, between 60 and 80%yield of gasoline is obtained with a leaded octane number in the range98-100.

Hydrocracking of gas oils has been integrated with hydrogen donordiluent cracking in such a manner as to produce ample quantities ofaromatic hydrocarbons in the hydrocracking step which can behydrogenated partially to produce excellent hydrogen donor diluents forHDDC conversion of residuum or residual oils. In addition to providingthe diluent for HDDC, this integration results in a number of otheradvantages. For example, the diluent fraction obtained from thehydrocracking operation has very low sulfur and, after beinghydrogenated and used as a hydrogen donor diluent, this fraction ends upas a stable, low sulfur heating oil which requires little or nofinishing treatment. Another advantage is the high octane gasolineobtained over a platinum hydrocracking catalyst supported on etaalumina. The high activity of this catalyst permits excellentconversions at high space velocity.

Other advantages will be evident as this refining scheme is discussed ingreater detail, particularly with respect to the hydrogen balancedoperations and the product distributions. Complete residuum reduction isobtained in this refining scheme together with a high octane gasolinepool.

The process is flexible and permits varying the severity of thehydrocracking and HDDC steps to vary product distribution and quality.In addition, the gasoline pool octane number can be varied by varyingthe quantity and the streams fed to the hydroforming step. The naphthafrom the HDDC step is preferably hydroformed. The present integratedhydrocracking-HDDC process also offers an excellent route to maximizemiddle distillates at the expense of gasoline, should that be desirable.Both HDDC and hydrocracking can be operated at mild conditions to givehigh selectivity to middle distillates.

In-the drawings:

cat

3,252,838 Patented May 24, 1966 FIG. 1 diagrammatically represents oneform of apparatus for carrying out the invention; and

FIG. 2 diagrammatically represents a modification of the apparatus shownin FIG. 1.

Referring now the drawings, the reference character 10 designates a linefor introducing whole crude petroleum oil into an intermediate part ofvertically arranged fractionator 12. The oil is fractionated into aplurality of fractions and a light hydrocarbon fraction, including gasesand boiling up to about 200 F., is taken overhead through line 14. Thiscut is normally fractionated further to obtain dry gas, LPG, and somepentanes plus higher boiling liquid products. The liquid products (andbutanes if desired) are added directly to the gasoline pool or they maybe treated to improve quality by desulfurization, isomerization, etc. Aheavy naphtha fraction boiling between about 200 F. and 430 F. iswithdrawn through line 16 from the upper portion of the fractionator 12.A kerosene fraction boiling between about 430 F. and 490 F. is withdrawnat a lower level from the fractionator 12 through line 18. A light gasoil fraction boiling between about 490 F. and 700 F. is withdrawn from alower portion of the fractionator 12 through line 22. A heavy gas oilfraction boiling between about 700 F. and 900 F. is withdrawn furtherdown from the lower portion of the fractionator 12 through line 24. Abottoms fraction higher boiling than about 700 F.-900 F. is withdrawnfrom the bottom of the fractionator 12 through line 26. In some cases itmay be desirable to withdraw a 700 F.+ stream from the bottom offractionator 12 through line 26 and make the separation into 700 F. to900 F. and 900 F.+ fractions in vacuum still 27 hereinafter described.

The heavy naphtha fraction boiling below about 430 F. and withdrawnthrough line 16 is mixed with hydrogen from line 28 and introduced intohydroforming zone 32. The temperature is maintained between about 800 F.and 1050 F. in hydroforming zone 32, the pressure is maintained betweenabout 0 p.s.i.g. and 800 p.s.i.g., and about 1000 s.c.f. to 15,000 s.c.fof hydrogen-containing gas per barrel of naphtha feed is used Thepreferred hydroforming catalyst is a platinum-alumina catalyst where thealumina contains about 0.001 to 5.0 wt. percent of platinum. The feedrate of naphtha is between about 0.1 and 10 w./w./hr. Instead of the200430 F. naphtha, other feedstock boiling ranges, such as 200350 B, maybe used to vary the hydroformer performance.

Other hydroforming catalysts such as molybdenaalumina,palladium-alumina, chromia-alumina, etc., as well as variousmodifications may be used. The platinum catalysts may containstabilizers such as silica to stabilize the surface area of the aluminaor thoria to prevent platinum crystal growth.

The preferred platinum-alumina catalyst may be used for both thehydroforming and hydrocracking operations. High activity is maintainedby regeneration and chlorine treating the catalyst after each cycle.Regeneration may be carried out in a number of ways but preferably it isaccomplished with air or flue gas at a pressure between about 0 and1,000 p.s.i.g. and at a temperature in the range of 800 to 1050 F. Afterregeneration, the precious metal catalyst on an acidic support ischlorine treated to enhance activity. Although chlorine is preferred forthis treatment, any known halogen compound, decomposable into freechlorine, non-metallic halide or aluminum halide may be used for thispurpose. It is also preferred to do the treating'in an oxidizingatmosphere and this can be accomplished by introduction of air whilechlorine treating.

During hydroforming, hydrogen is produced in a suflicient amount to berecycled to the hydroforming step, to supply hydrogen for ahydrocracking step to be presently described and for partiallyhydrogenating high boiling aromatic compounds to produce hydrogen donordiluents to be used in converting residual oil in a step hereinafter tobe described. In some cases additional hydrogen is available forhydrodesulfurization of heating oil, etc.

The hydroformed products are passed through line 34 to a knockout drumor fractionating tower 36. In this tower 36, hydrogen gas containingsome gaseous hydrocarbons is withdrawn overhead through line 38 and aportion recycled through line 28 to the hydroforming zone 32. Anotherportion of the hydrogen-containing gas is passed through line 42 and anyexcess hydrogen can be removed from the system through line 44. A lightgaseous hydrocarbon fraction is withdrawn asa side stream through line46 from an upper portion of tower 36. A gasoline fraction is withdrawnfrom an intermediate portion of the tower 36 through line 48. When thefeed to hydroformer 32 contains material boiling in the 380-430 F.range, some 430 F.| bottoms may be produced and this will be withdrawnthrough line 54. This bottoms fraction is preferably added to the feedto hydrocracker 58 through line 60.

A kerosene fraction is withdrawn from tower 12 through line 18 for useas kerosene or heating oil. Preferably, this fraction is hydrocrackedtogether with the gas oil from line 22 or separately in a blockedoperation to make specialty fuels or aromatics. In one prefer-redoperation, a 200-370 F. naphtha fraction is hydroformed and the entire370-650 F. fraction is hydrocracked.

The gas oil fraction withdrawn from the fractionating tower 12 throughline 22 is mixed with hydrogen-containing gas from line 61 and passedthrough the hydrocracking zone 58 maintained at a temperature betweenabout 400 and 1050 F., and a pressure between about 200 and 10,000p.s.i.g. The feed rate of the gas oil to the zone 58 is between about0.1 and w./ w./ hr. About 2,000 to 20,000 s.c.f. of hydrogen-containinggas per barrel of feed are used. Additional hydrogen is recycled to line22 through line 62. The catalyst in the hydrocracking zone 58 ispreferably platinum-alumina similar to that used in the hydroformingzone but other hydrocracking catalysts such as cobalt molybdate onalumina, precious metals such as platinum or palladium on supports suchas alumina, silica-alumina or molecular sieves, nickel sulfide onalumina, etc., may be used. The activity of platinum catalysts isimproved by the addition of chloride.

Some of the gas oil from line 22 may be withdrawn through line 64 as aheating oil product. Preferably, additional gas oil from a later stagein the process is also returned to the hydrocracking zone 58 throughline 60.

The hydrocracked products are passed through line 68 into a knockoutdrum or fractionating tower 72 to separate hydrogen-containing gasoverhead through line 74 and a normally gaseous hydrocarbon stream iswithdrawn through line 76 as a side stream from the upper portion oftower 72. The hydrogen-containing gas in line 74 contains someimpurities such as sulfur and nitrogen-containing compounds and ispreferably passed through conventional scrubbing means 78 and thepurified hydrogen-containing gas is recycled to the hydrocracking zone58 through line 6-2. A portion of the hydrogencontaining gas can be bled01f through line 82 and removed from the process.

Returning to the tower 72, when using the tower as a knockout drum, agasoline fraction is withdrawn as a side stream through line 84 from anintermediate portion of the tower 72. The bottoms fraction withdrawnthrough line 86 is a relatively light fraction boiling above about 430F. When functioning as a fractionating tower, valved line 88 is used towithdraw a higher boiling fraction from the lower portion of thefractionating tower 72. This fraction boils up to about 700 F. so thatin this form of the invention the bottoms withdrawn through line 86 willcontain material boiling above about 700 F.

In either case the bottoms withdrawn from the tower 72 through line 86are mixed with hydrogen from line 42 and passed to a hydrogenation zone92. This bottoms fraction contains higher boiling aromatic compoundswhich are partially hydrogenated in the hydrogenation zone 92 usingconventional hydrogenation conditions and introducing about 50 to 1000s.c.f. of hydrogen per barrel of the bottoms fractions. The temperatureis maintained between about and 750 F. and the pressure between about 50and 1000 p.s.i.g. in the hydrogenation zone 92. The oil feed rate isbetween about 0.1 and 10 w./w./hr. As the bottoms fraction containsimpurities such as sulfur, it is preferable to employ a relativelysulfur-insensitive catalyst, such as molybdenum sulfide or tungstennickel sulfide, which normally requires operation at the highertemperatures and pressures.

The hydrogen donor diluent precursor used in this invention is adistillate material or a bottoms material boiling above about 430 F. andpreferably above 700 F. and should have an aromatic ring content aboveabout 40 wt. percent. Partially hydrogenated condensed or polycyclicaromatic ring compounds contain aromaticnaphthenes having one or morearomatic nuclei which increase the reactivity of the naphthenichydrogens and cause the molecule to function as a superior hydrogendonor. By partial hydrogenation is meant an extent of hydrogenationsutficient to introduce on the average one to three hydrogen moleculesinto the aromatic-naphthenic donor molecule, while leaving one or morerings unhydrogenated. This results in a diluent donor having a hydrogento carbon atomic ratio in the range of 0.7 to 1.6. The donor diluentpicks up enough easily removable hydrogen to be effective as a hydrogendonor but not enough to approach saturation or to convert itsubstantially to naphthenes. Reference is made to Langer Patent2,953,513 granted September 20, 1960, and the disclosure there isincorporated here by reference.

The amount of hydrogen which must be added to the hydrogen donor diluentprecursor will depend upon the feedstock and the conditions used in thehydrocracking stage (catalyst, hydrogen pressure, temperature, crackingseverity, etc.). The more highly aromatic precursors can take up to1,000 s.c.f. H /bbl. without harming the donor properties. When thehydrocracker is operated at high hydrogen consumption, the diluentprecursor will be less aromatic and will require little additionalhydrogen to be an effective hydrogen donor diluent. Generally, the mostetficient hydrocracking conditions will yield a hydrogen donor diluentprecursor which requires between about 100 and 500 s.c.f. added H /bbl.for the most effective hydrogen donor activity.

The recycle hydrogen donor diluent stream from a later stage in theprocess is passed through line 94, mixed with the bottoms stream in line86 and introduced into hydrogenation zone 92. The partially hydrogenatedhigher boiling aromatic compounds are withdrawn from the hydrogenationzone 92 through line 96 and passed to the non-catalytic HDDC zone 98.Also introduced into the HDDC zone 98 is the bottoms fraction fromfractionator 12 through line 99 or a portion of the bottoms fractionwithdrawn from fractionating tower 12. The bottoms fraction in line 26is introduced into the vacuum distillation zone 27 to separate overheada higher boiling or heavy gas oil fraction boiling above about 700 F.900F. and withdrawn through line 104. The product from 104 may be used asfeed to catalytic cracking or hydrocracking, or as heavy fuel. Thebottoms fraction from vacuum distillation zone 27 is withdrawn throughline 186 and is passed into the HDDC zone 98. This fraction has aboiling point above about 1100 F.

In the HDDC zone the temperature i maintained between about 700 F. and1000 F. and the pressure between about 100 and 5000 p.s.i.g. so that theconversion is carried out predominantly in the liquid phase. The feedrate of bottoms feed is between about 0.1 and v./v./hr. The hydrogenateddiluent from line 96 is used in an amount about 0.1 to 2 parts by weightper 1 part by weight of residual feed passing through line 106.

In the HDDC step or zone the residuum or residual oil is converted tolower boiling hydrocarbons normally in the absence of extraneoushydrogen and in the absence of catalyst and is operated to giveessentially 100% conversion on the fresh residuum per pass. An effectivedonor diluent used in proper concentration will provide sufficientactive hydrogen to prevent coke formation but under some conditions itmay be desirable to supplement the donor diluent with molecularhydrogen. In such cases the condensed ring aromatic compounds of thediluent act as homogeneous hydrogenation catalysts by consumingmolecular hydrogen and transferring it to the cracked products fromresiduum. The reaction products from the HDDC zone 98 are passed throughline 108 to fractionating tower 112 to separate lower boiling materialfrom higher boiling liquids.

The bottoms from fractionating tower 112 are withdrawn through line 114and recycled to the line 26 which feeds material to the vacuumdistillation zone 27. A portion of this recycled material may bewithdrawn from the process through line 116 to prevent accumulation ofash in the system. Alternatively, the bottoms from tower 112 may berecycled to the HDDC zone 98 through lines 114 and 117. Likewise, thebottoms from tower 12 may be used as feed to the HDDC zone 98 byproceeding through line 26 and line 99 which by-passes the vacuum tower27. In the preferred operation, bottoms from both 12 and 112 are sent tovacuum tower 27 to recover distillate products and decrease the volumeof feed to HDDC zone 98- A heavy gas oil fraction is withdrawn from thebottom of fractionating tower 112 through line 118. This fraction may beused as feed to catalytic cracking or hydrocracking, or as a fuelproduct. In a preferred operation to maximize gasoline yield, the heavygas oil is catalytically cracked with recycle to 100% conversion. Higherup in the tower 112 a light gas oil fraction is withdrawn through line122 and a portion of this gas oil fraction can be withdrawn from thesystem through line 124 as a low sulfur heating oil. A portion or allthe oil fraction in line 124 can be recycled through line 68 for passagethrough hydrocracking zone 58. Any excess of bottoms from line 86 overthat required for HDDC may also be recycled to hydrocracker 58 throughline 60. Another portion of the light gas oil from line 122 may bepassed through line 94 and recycled to the hydrogenation zone 92 ashereinbefore described. This fraction contains aromatic compounds whichare partially hydrogenated in the zone 92 and form excellent diluentsfor the HDDC step.

Further up in the tower 112 a heavy naphtha fraction is withdrawn as aside stream through line 126 and this fraction is preferably recycled toline 16 to be hydro formed along with the virgin naphtha from tower 12.From the upper portion of the tower 112 a light naphtha fraction iswithdrawn as a side streamthrough line 128 and added to the gasolinepool. In some cases it may be desirable to improve quality of thefraction in line 128 by desulfurization, hydrofinishing, isomerization,etc. Withdrawn overhead through line 132 is a gaseous fractioncontaining C hydrocarbons and lower.

The heavy gas oil fraction withdrawn through line 24 from tower 12 ispreferably used as feed to catalytic cracking or hydrocracking. Althoughthe catalytic cracking and its companion fractionation facilities havenot been shown in the drawing, it is evident that further economies canbe effected by integration with the various fractionation facilities ofthis invention.

Referring now to FIG. 2, whole crude oil is passed through line 152 intofractionating tower 154 to separate the lower boiling hydrocarbons andgas overhead through line 156. A heavy naphtha fraction is withdrawnthrough line 158 and passed to hydroforming zone 162 which is operatedunder similar conditions to those described in connection with FIG. 1.Hydrogen-containing gas from line 164 is also introduced into line 158.

The hydroformed products are passed through line 166 to fractionatingtower 168 to separate hydrogen-containing gas which is withdrawnoverhead through line 172 and in part recycled to the hydroforming zone162 through line 164. A normally gaseous hydrocarbon fraction iswithdrawn from the upper part of the tower 168 through line 174 as aside stream. Lower down a gasoline fraction is withdrawn as a sidestream through line 176. The bottoms fraction withdrawn through line 178contains hydrocarbons higher boiling than about 430 F. It is mixed withthe gas oil in line 180 and hydrocracked in zone 181. Make-up hydrogencan be introduced into line 164 through line 182. Excess hydrogen can bewithdrawn through line 184.

A kerosene fraction is withdrawn through line 186 from tower 154 andtreated as described earlier in FIG. 1, tower 12, line 18. Further downin the tower 154 a gas oil fraction is withdrawn through line 188. Thisfraction may be used as heating oil, but it is preferably hydrocrackedor catalytically cracked. In one preferred operation to maximizegasoline yield, the entire boiling range between heavy naphtha andvacuum gas oil may be hydrocracked to complete conversion in a recycleoperation. Lower down in the tower 154 a higher boiling fraction or aheavy gas oil boiling between about 650 F. and 1050 F. is withdrawnthrough line 180 and passed into the hydrocracking zone 181 which issimilar to that described at 58 in connection with FIG. 1. Alsointroduced with the feed is hydrogen-containing gas from line 196 whichin part forms hydrogen-containing gas recycled from the hydrocrackingstep and in part from line 198 from the hydroforming step.

The hydrocracked products are passed through line 202 to a knockout drum204 for separating gases from by drocarbon liquids. Using a heavy gasoil as feed for the hydrocracking step yields aromatic material boilingin the range of 600 F.1000 P. which is suitable for use as a hydrogendonor diluent in HDDC. The gases containing hydrogen pass overheadthrough line 266 and a conventional scrubber 208 for removing impuritiesfrom the hydrogen-containing gas and the gas is recycled through line196 to the hydrocracking zone 181. A portion of the gas may be bled offfrom line 196 through line 212.

A bottoms fraction from knockout drum 204 containing substantially allthe normally liquid hydrocarbons is withdrawn through line 214 andpassed to fractionating tower 216.

In tower 216, C hydrocarbons are withdrawn overhead through line 218 anda C fraction is withdrawn from the upper portion of the tower 216through line 222. A naphtha fraction is withdrawn from the tower 216 asa side stream through line 224 and is preferably recycled to thehydroforrning zone 162.

Lower down in the fractionating tower a gas oil fraction boiling in therange of 430 F.700 F is withdrawn through line 226 and passed throughthe hydrogenation zone 228 into which hydrogen is introduced throughline 232 for partially hydrogenating aromatic hydrocarbons to producehydrogen donor diluent compounds. The bydrogenation zone 228 is similarto that at 92 described-in connection with FIG. 1. Hydrogen from thehydroforming step is used. In addition, a heavy gas oil fraction boilingbetween about 700 F. and 900 F. is withdrawn from the lower portion ofthe fractionating tower 216 and is withdrawn as a side stream throughline 234 and may be recycled through line 236 to the hydrogenation zone228 or may be recycled through line 238 to the hydrocracking zone 181 orcatalytically cracked. Line 239 shows leading the stream similar to thatin line 238 to bydrocracking zone 181.

The bottoms fraction boiling above about 900 F. from fractionating tower216 is withdrawn through line 242 and mixed with the bottoms withdrawnthrough line 244 from the main fractionating tower 154 and this mixtureis passed into the vacuum distillation tower 246. A portion of thestream in line 242 can be bled off through line 247 to prevent build upof ash in the system. The vacuum gas oil fraction boiling above about900 F. is withdrawn overhead through line 248 and contains virginconstituents and also HDDC constituents. This stream is preferably usedas feed to catalytic cracking or lended into heavy fuel. The bottomsfrom the vacuum distillation zone 246 are withdrawn through line 252 andintroduced into the HDDC zone 254 which is similar to the HDDC zone 98shown and described in connection with FIG. 1. The hydrogenated productsfrom by drogenation zone 228 are passed through line 256 into HDDC unit254 for converting the residual oil withdrawn from the vacuum tower 246.

The reaction products from HDDC zone 254 are passed through line 258 andflashed to a 430 F. cut point in fractionating tower 262. A C fractionis passed overhead through line 264 and a light naphtha fraction iswithdrawn as a side stream from the upper portion of the tower throughline 266. A heavy naphtha fraction is withdrawn as a side stream fromthe tower 262 through line 268 and is preferably recycled to thehydroforming zone 162.

The bottoms boiling above about 430 F. are Withdrawn from the tower 262through line 272 and recycled to the fractionating tower 216 where theyare further fractionated in the hydrocracking products fractionator 216to separate and recover spent donor diluent mixed with make-up diluentprecursor from hydrocracking 181.

Referring now to FIG. 1, an example will be given in which 200,000 b.d.of whole petroleum crude oil is separated and processed. Using WestTexas crude oil and fractionating it in the tower 12, the light naphthaoverhead fraction in line 14 has a boiling point up to about 200 F. andabout 16,000 b./d. are removed and placed in the gasoline pool. Theheavy naphtha fraction in line 16 has a boiling range between about 200and 430 F. and the amount of naphtha withdrawn is about 47,000 b./ d.

The kerosene fraction withdrawn through line 18 has a boiling range ofabout 430 to 490 F. and the amount withdrawn is about 13,000 b./d. Thehydrocracking feed stock in line 22 has a boiling range of about 490 to700 F. and the amount withdrawn is about 42,000 b./d. The heavy gas oilwithdrawn through line 24 has a boiling range between about 700 and 900F. and the amount withdrawn is about 28,000 b./d. The bottoms withdrawnthrough line 26 boils above about 900 F. and the amount withdrawn isabout 54,000 b./d.

The 200 to 430 F. fraction is heated up and passed to the hydroformingzone 32 together with hydrogencontaining gas introduced through line 28.The amount of hydrogen introduce-d is about 5,000 s.c.f/b. of feed. Thetemperature in zone 32 is about 930 F. and the pressure about 250p.s.i.g. The catalyst is a platinumalumina catalyst containing about 0.6wt. percent platinum. The reaction products are passed through line 34and fractionated in the tower 36 to separate a C 430 F. gasolinefraction of about 95 research octane number. The amount of this gasolinefraction is about 39,900 b./d.

The 490 to 700 F. hydrocracking feed is passed through the hydrocrackingzone 58 together with about 5,000

Yields Wt. Vol. 13 D percent percent The octane number of the gasolineis about 89.7 research clear and 88.3 motor+3 cc. lead. Operation atlower temperatures, such as 600750 F., produces much higher yields ofgasoline but somewhat lower octane number. If yield is maximized in thehydrocracking stage, the gasoline may require hydroforming to improvequality.

The bottoms from the knockout drum 72 in an amount of about 12,180 b./d.pass through line 86 to the hydrogenation zone 92 together with 11,000b./d. recycle from line 94. The recycle in line 94 has a boiling rangebetween about 430 F. and 650 F. Hydrogen-containing gas from line 42 ispassed to zone 92. The aromatic bottoms fraction in line 86 boils in therange of about 430 to 700 F. and this fraction together with the recyclefrom line 94 is partially hydrogenated over a sulfur resistant catalystsuch as cobalt molybdate, until about to 1000, preferably 200 to 600,cubic feet of hydrogen has been added per barrel of feed to thehydrogenation zone 92 to produce hydrogen donor diluent compounds. Thehydrogen donor diluent fraction is then mixed with about an equivalentamount of crude residuum from line 106 plus the unconverted recyclebottoms from the HDDC step. The oil feed in line 106 to the noncatalyticHDDC zone 98 includes 26,000 b./d. of virgin residuum and 19,000 b./d.of recycle HDDC. Data on the HDDC conversion of the residuum are asfollows:

ing 12,000 490/700 F. Diluent recycle 11,000 Temperature, F. 880Pressure, p.s.i.g 400 Feed rate, v./hr./v. 4 Yields on totalfeed-i-diluent, b./d,:

C gas (2.3 wt. percent) C (0.9 vol. percent) 620 C /430 F. (16.8 vol.percent) 11,400 430/650 F. (28.4 vol. percent) 19,300 650/1l00 F. (27.1vol. percent) 18,400 1l00 F.+ (28.0 vol. percent) (Recycle) The productsfrom the HDDC step are fractionated in a separate atmospheric tower 112to provide components for recycle as well as the final products. Thenaphtha formed in the HDDC step is of relatively low octane number andis preferably separated to provide a fraction suitable for hydroforming.The 900 F bottoms from the HDDC step are withdrawn from tower 112through line 114 and vacuum distilled to about 1100 F. cut point in thesame vacuum distillation tower 27 used in the distillation of the cruderesidual oil thereby effecting a blending of the recycle bottoms withfresh residuum which is withdrawn through line 106 and passed to theHDDC step or zone 98.

The flexibility of the process of the present invention is apparentsince product distribution and quality can be varied at will by varyingthe severity of hydrocracking, HDDC and catalytic cracking, and thegasoline pool octane number can be varied by varying the quantity andthe streams fed to the hydroforming step. Using the combination of stepsshown in FIG. 1 and hydroforming the 200 F. to 430 F. virgin naphtha andthe naphtha formed by the HDDC conversion to obtain 48,520 b./d. ofgasoline, hydrocracking the 490 to 700 F. gas oil to 42.3 vol. percentgasoline to obtain 21,277 b./d. of gasoline and catalytically crackingthe heavy gas oil 700 to 1100 F. to 45 vol. percent gasoline to obtain33,480 b./d. of gasoline, a yield of 59.6 vol. percent of C 430 F. or119,277 b./d. of gasoline is obtained with 92.1 research octane number(clear) and 100 octane number (leaded). Inclusion of C polymer and Calkylate into the gasoline pool will raise the yield to over 60 vol.percent on crude and the octane number still higher. Adding thehydroformer bottoms and the 430-490 F. kerosene fraction to thehydrocracker feed and operating the hydrocracker at lower temperaturesto maximize gasoline yield increases the total gasoline yield to about160,000 b./d. or 80 vol. percent on crude.

The maximum yield of gasoline from West Texas crude petroleum oil byconventional processing is about 52.9 vol. percent including C s and Cpolymer, obtained by catalytic cracking of the total gas oil andvisbreaking the residuum. The gasoline obtained in this conventionalprocessing has only 88.6 research octane number clear. If hydroformingand C alkylate are included, the yield only increases to about 55% andthe octane number to about 92. Thus, it is apparent that the process ofthe present invention following the steps in FIG. 1 yields much moregasoline of higher octane number than is obtainable by conventionalprocessing. Further, the present invention produces only distillateproducts since the HDDC conversion completely eliminates residual fuels.

If desired, the process can be changed to remove only a bottoms fractionboiling mainly in the range of 650 to 700 F. from tower 72 and, as thisbottoms fraction contains aromatic hydrocarbons, it is an especiallygood feed feed for the hydrogenation step for zone 92 where the aromatichydrocarbons are partially hydrogenated to produce the hydrogen donordiluent compounds. The hydrogen donor diluent makeup requirements forthe HDDC conversion can be easily satisfied by varying the amount ofaromatic hydrocarbon bottoms Withdrawn from the fractionator 72 used forfractionating the hydrocracked products. In this case, the major portionof the hydrogen donor diluent is obtained by recycling essentially allof a 500-700 F. cut from fractionator 112. A 430700 F. fraction would beseparated in tower 72 according to this process variation and withdrawnthrough line 83. This product is a stable low sulfur, heating oil.

Instead of using a relatively narrow aromatic hydrocarbon fraetion, thehydrocracker feed and the product boiling ranges may be varied to yieldan aromatic hydrocarbon fraction boiling in the range of about 600l000F. which is also suitable for use as a hydrogen donor diluent in theHDDC conversion step. The choice of boiling range permits flexibility inthe product distribution from the HDDC conversion. In the form shown inFIG. 2 the HDDC products are flashed to a. 430 F. cut point. The 430 F.|bottoms fraction is fractionated further in the fractionator 216 used toseparate the hydrocracked products thereby adding fresh diluent makeupcontinuously to the spent diluent.

The octane number of the gasoline from hydrocracking can be varied bychanging the hydrocracking severity. Furthermore, the properties of the430 F.| bottoms can be varied appreciably by changing the crackingseverity. Thus by integrating hydrocracking with HDDC, one cantailor-make the best diluent for HDDC. This is shown in the followingtable:

By increasing the hydrocracking severity from 47% to 68% conversion, itcan be seen that the 430 F.+ bottoms increased in aromaticity to aremarkable extent as shown by the decrease in API gravity and the greatdecrease in aniline point. It has been shown that highly aromaticrefinery streams boiling above 430 F. are excellent hydrogen donordiluents upon partially hydrogenating the condensed ring aromatics. Thearomatic bottoms from the platinum hydrocracking step boil in the range430700 F. and this fraction is utilized in the HDDC conversion step asshown in FIGS. 1 and 2.

Although several alternative refining schemes utilizing integratedhydrocracking-HDDC processes have been discussed, various othermodifications can readily be visualized by those skilled in the art as aresult of these disclosures. It is within the scope of this invention toinclude the various modifications which are necessary to fit thehydrocracking-HDDC process to any particular refinery. For example, thisprocess can be combined in many different ways with a variety of otherrefining processes such as catalytic cracking, thermal cracking,isomerization, hydrofining, polymerization, etc. Similarly, it isobvious that each refinery situation will require different cut pointsfor the various products as well as different choices of streams tosegregate for specialty products or to combine or recycle to the variousprocesses. Likewise, there will be wide variations in the conditionsunder which the various processes are operated depending on such thingsas crude oil types, desired product distribution, etc. Such variationsand modifications are considered as coming within the teachings of thisinvention.

What is claimed is:

1. A process for treating hydrocarbons which includes separating a wholepetroleum crude oil into a naphtha fraction, a gas oil fraction, and abottoms fraction boiling above about 700 F., hydroforming said naphthafraction to produce gasoline, hydrogen and higher boiling hydrocarbons,catalytically hydrocracking said gas oil fraction to produce gasolineand a higher boiling hydrocarbon fraction including polycyclic aromatichydrocarbons, recycling hydrogen from said hydroforming step to saidhydroforming and hydrocracking steps, partially hydrogenating saidhigher boiling fraction to produce partially hydrogenated polycyclicaromatic hydrocarbons as hydrogen donor diluents, mixing at least aportion of said bottoms fraction with said partially hydrogenatedpolycyclic aromatic hydrocarbons, passing said mixture to a thermalconversion zone to non-catalytically convert said bottoms fraction tolower boiling hydrocarbons including naphtha, and recovering a naphthafraction from the last mentioned converted hydrocarbons.

2. A process according to claim 1 wherein said bottoms fraction isvacuum distilled to separate lower boiling hydrocarbons to produce asecond bottoms fraction boiling above about 900 F. and said secondbottoms fraction is passed to said non-catalytic thermal conversion steptogether with said partially hydrogenated polycyclic aromatic compounds.

3. A process according to claim 1 wherein said rcovcred naphtha fractionis recycled to said hydroforming step to produce additional gasoline.

4. A process according to claim 1 wherein the conversion products fromsaid non-catalytic thermal conversion step are fractionated to separatea hydrogen donor diluent fraction containing partially hydrogenatedaromatic condensed ring compounds and said last mentioned fraction isrecycled to said non-catalytic conversion step.

5. A process according to claim 1 wherein the products from the saidnon-catalytic thermal conversion step are fractionated to separate aspent diluent fraction and said spent diluent fraction is recycled tosaid partially hydrogenating step to produce partially hydrogenatedpolycyclic aromatic hydrocarbons as hydrogen donor diluents and saidpartially hydrogenated fraction is recycled to said non-catalyticthermal conversion step.

6. In a hydrocarbon conversion process wherein a naphtha fraction ishydroformed and hydrogen is produced, a gas oil fraction iscatalytically hydrocracked and a bottoms or residual fraction boilingabove about 900 F. is separated from crude petroleum oil, theimprovement which comprises catalytically hydrocracking at a temperatureof about 1015 F. said gas oil fraction with hydrogen added from saidhydroforming step to produce gasoline and a higher boiling fractioncontaining condensed ring aromatic hydrocarbons boiling above about 430F, partially hydrogenating said higher boiling fraction to introduce onthe average one to three hydrogen atoms into said aromatic hydrocarbonmolecule and to produce partially hydrogenated condensed ring aromatichydrocarbons which are useful as hydrogen donor diluents, mixing atleast a portion of said partially hydrogenated condensed ring aromatichydrocarbons with said bottoms or residual crude oil fraction, passingthe last mentioned mixture through a non-catalytic conversion zonemaintained at a temperature between about 700 F. and 1000 F., a pressurebetween about 100 p.s.i.g. and 5000 p.s.i.g., at an oil feed ratebetween 0.1 v./v./hr. and v./v./hr. and using said partiallyhydrogenated condensed ring aromatic hydrocarbons in a weight ratio ofabout 0.1 to 1 to 2 to 1 said bottoms or residual fraction to producelower boiling hydrocarbons.

7. In a hydrocarbon conversion process wherein a naphtha fraction ishydroformed and hydrogen is produced, a gas oil fraction iscatalytically hydrocracked and a bottoms or residual fraction boilingabove about 900 F. is separated from crude petroleum oil, theimprovement which comprises catalytically hydrocracking said gas oilfraction with hydrogen added from said hydroforming step to producegasoline and a higher boiling fraction containing condensed ringaromatic hydrocarbons boiling above about 430 F., partiallyhydrogenating said higher boiling 'fraction to produce partiallyhydrogenated condensed ring aromatic hydrocarbons which are useful ashydrogen donor diluen'ts, mixing at least a portion of said partiallyhydrogenated condensed ring aromatic hydrocarbons with said bottoms orresidual crude oil frac tion, and passing the last mentioned mixturethrough a non-catalytic thermal conversion zone to produce lower boilinghydrocarbons.

8. The process according to claim 7 wherein the conversion products fromsaid non-catalytic thermal conversion zone are fractionated to separatea spent hydrogen diluent, said spent hydrogen diluent is recycled tosaid partial hydrogenation step to produce fresh hydrogen donor diluentand said fresh hydrogen donor diluent is recycled to said non-catalyticthermal conversion zone.

9. A process according to claim 6 wherein said lower boilinghydrocarbons are treated to recover a naphtha fraction and the naphthafraction is recycled to the hydroforming step.

10. A process according to claim 1 wherein all the hydrogen necessaryfor the hydroforming step, the hydrocracking step and the hydrogenationof the polycyclic aromatic hydrocarbons is obtained from saidhydroforming step.

11. A process according to claim 1 wherein substantially all of saidcrude oil feed is converted to distillate stocks in the process.

12. A process according to claim 1 wherein the polycyclic aromatichydrocarbons which are partially hydrogenated to form hydrogen donordiluents are obtained entirely in the process without need of makeupextraneous donor diluents.

References Cited by the Examiner UNITED STATES PATENTS 2,843,530 7/1958Langer et al. 20856 2,932,611 4/1960 Scott et al. 208 3,008,895 11/1961Hansford et al. 208112 3,019,180 1/1962 Schreiner et al. 20879 3,092,5676/1963 Kozlowski et al. 20857 3,132,086 5/1964 Kelly et al 2081123,147,206 9/1964 Tulleners 208111 DELBERT E. GANTZ, Primary Examiner.

ALPHONSO D. SULLIVAN, Examiner.

A. RIMENS, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,252,888 May 24, 1966 Arthur w. Langer, Jr., et a1.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

In the drawings, Sheet 1, FIG. 1, in approximately the middle of thefigure, for "8" read 86 column 11, line 22, for "atoms" read moleculesSigned and sealed this 3rd day of December 1968.

EAL)

test:

ward M. Fletcher, Jr. EDWARD J. BRENNER testing Officer Commissioner ofPatents

1. A PROCESS FOR TREATING HYDROCARBONS WHICH INCLUDES SEPARATING A WHOLEPETROLEUM CRUDE OIL INTO A NAPHTHA FRACTION, A GAS OIL FRACTION, AND ABOTTOMS FRACTION BOILING ABOVE ABOUT 700*F., HYDROFORMING SAID NAPHTHAFRACTION TO PRODUCE GASOLINE, HYDROGEN AND HIGHER BOILING HYDROCARBONS,CATALYTICALLY HYDROCRACKING SAID GAS OIL FRACTION TO PRODUCE GASOLINEAND A HIGHER BOILING HYDROCARBON FRACTION INCLUDING PLYCYCLIC AROMATICHYDROCARBONS, RECYCLING HYDROGEN FROM SAID HYDROFORMING STEP TO SAIDHYDROFORMING AND HYDROCRACKING STEPS, PARTIALLY HYDROGENATING SAIDHIGHER BOILING FRACTION TO PRODUCE PARTIALLY HYDROGENATED POLYCYCLICHYDROCARBONS AS HYDROGEN DONOR DILUENTS, MIXING AT LEAST A PORTION OFSAID BOT-